Flow transducer muff

Abstract: The invention relates to a flow transducer muff (2) for positioning an essentially square-angled parallelepiped-shaped flow transducer (24) in an expiration channel of a ventilator. The flow transducer muff (2) comprises a first muff half (4) and a second muff half (6), devised for connection to both sides of the flow transducer (24), and a connecting link (8), attached to the muff halves (4, 6), so they can be bent around the connecting link (8).

Description: This invention relates to a flow transducer muff for positioning an essentially square-angled parallelepiped-shaped flow transducer in an expiration channel of a ventilator, comprising a first muff half and a second muff half, devised for connection on both sides of the flow transducer. Expired gas flow is measured in a flow transducer on the expiration side of a ventilator. The flow transducer is retained in position in the expiration channel with a flow transducer muff which forms a gas-tight connection to the flow transducer. The Operating Manual of the Servo Ventilator 900C, AG 0888 12, August 1988, Siemens-Elema AB, page 10: 2-3, describes one such flow transducer muff. In principle, the known flow transducer muff consists of two halves which are connected on both sides of the flow transducer. The two muff halves are identical in shape, so there is a risk of the flow transducer being reinstalled in a reversed position in the ventilator after cleaning. One object of the invention is to achieve a flow transducer muff which assures that the flow transducer is correctly positioned when installed in the expiration channel. Another object of the invention is to achieve a flow transducer muff which is simple to manufacture, provides a secure, gas-tight connection to the flow transducer, while simultaneously facilitating connection of the flow transducer, and reduces the number of components in the expiration channel. One such flow transducer muff is achieved in accordance with the invention by a connecting link, attached to the first muff half and to the second muff half so the muff halves can be bent around the connecting link. With the connecting link, the flow transducer muff consists of a single integrated unit. The connecting link also provides an orientation for the flow transducer, ensuring that it is positioned in the right direction. Since the connecting link is elastically devised, the two muff halves can be readily bent around it when the flow transducer is to be connected to the flow transducer muff or disassembled. In conjunction herewith, it is advantageous if the connecting link comprises a thin, elastic disc whose width is largely identical to the diameter of the muff halves. The flow transducer muffs becomes more stable because the connecting link has a width which is generally the same as the diameter of the muff halves. In order to ensure that the flow transducer really is positioned in the correct direction in the flow transducer muff, it is advantageous if the muff halves is devised with at least one support boss against which at least one of the flow transducer's end surfaces presses when the flow transducer is attached. Since the flow transducer's opening is not at the center of the flow transducer, the support boss means that the flow transducer can only be connected to the flow transducer muff in one way. To ensure that the flow transducer muff is correctly placed in the expiration channel, it is advantageous if the muff halves are asymmetrically devised so the flow transducer can only be connected to the expiration channel in one way. The asymmetry of the muff halves can be achieved either by giving them different shapes or by having different shapes for the connections to other components in the expiration channel. A refinement of the flow transducer muff is achieved in accordance with the invention in that the muff halves and the connecting link are made in a single piece, preferably by die-casting. The invention will now be described in greater detail below, referring to three figures in which FIG. 1 shows one embodiment of the flow transducer muff according to the invention; FIG. 2 shows a cross-section of the flow transducer muff; and FIG. 3 shows the flow transducer muff with a connected flow transducer. The flow transducer muff 2 in FIG. 1 is die-cast in a single piece and made from an elastic material. The flow transducer muff 2 consists, in principle, of three parts, a first muff half 4, a second muff half 6 and a connecting link 8. The connecting link 8 is provided with a groove 10 which terminates in an open hole 12 to make it possible for the two muff halves 4, 6 to be bent around the connecting link 8. To ensure that the flow transducer muff 2 is correctly installed in an expiration channel of a ventilator, the muff halves 4, 6 have been devised in different ways at the respective connection end. There is an opening 14 in the end of the second muff halve 6 which fits a corresponding part in the expiration channel so the flow transducer muff 2 makes a correct fit. In FIG. 2 is shown a cross-section along line A-A on the flow transducer muff 2. Here, it can be clearly seen that the connecting link 8 has a thin disc which holds the two muff halves 4, 6 together. To ensure that the flow transducer is correctly placed in the flow transducer muff 2, the connecting link 8 has a first support boss 18 and a second support boss 20 against which the flow transducer is pressed when connected to the flow transducer muff 2. Connection of the flow transducer is through a connection opening 22 in the respective muff half 4, 6. Here, the flow transducer is arranged with a corresponding circular shoulder. FIG. 3 shows the flow transducer muff 2 with a flow transducer 24 connected. Other parts of the flow transducer muff 2 are identical to the parts described in FIG. 1.

Claims: A flow transducer muff for positioning an essentially square-angled parallelepiped-shaped flow transducer (24) in an expiration channel of a ventilator, comprising a first muff half (4) and a second muff half (6), devised for connection to both sides of the flow transducer (24), characterized by an elastic connecting link (8) attached to the first muff half (4) and to the second muff half (6) so the muff halves (4, 6) can be bent around the connecting link (8). A flow transducer muff according to claim 1, characterized in that the connecting link (8) comprises a thin, elastic disc (16) whose width is largely identical to the diameter of the muff halves. A flow transducer muff according to claim 1 or 2, characterized in that the muff halves (4, 6) are devised with at least one support boss (18, 20) against which at least one of the flow transducer's (24) end surfaces presses when the flow transducer is attached. A flow transducer muff according to any of the above claims, characterized in that the muff halves are asymmetrically devised so the flow transducer can only be connected to the expiration channel in one way. A flow transducer muff according to any of the above claims, characterized in that the muff halves (4, 6) and the connecting link (8) are made in a single piece, preferably by die-casting.

Inventors: EDSTROEM ROLF, ERIKSSON STURE, EDSTROEM, ROLF, ERIKSSON, STURE, Edström, Rolf
Applicants: SIEMENS ELEMA AB, SIEMENS-ELEMA AB
Application year: 1994
Main classification: G01F15
IPC codes: A61M16, G01F15